Аннотация:Two donor–acceptor (D–A) backbone copolymers with different fused ring8 acceptors, i.e., dithieno [2,3-e:30,20-g]isoindole-7,9(8 H)-dione (DTID) and9 dithieno[3 0,20:5,6;200,300:7,8]naphtho[2,3-d]imidazol-9(10 H)-one (DTNID) and10 same benzo[1,2-b:4,5-b0]dithiophene with alkylated aromatic side as side chainsQ4 11 (BDTT) donor, denoted as P133 and P135 are synthesized and used as donor12 along with narrow bandgap nonfullerene Y6 acceptor for the preparation of13 polymer solar cells (PSCs). The dielectric constant of P135:Y6 is higher than that14 of P133:Y6 due to the strong electron deficient ability of DTNID compared to15 DTID, which fostered exciton dissociation and charge transport, constrained16 charge recombination, and ultimately boosted the power conversion efficiency17 (PCE) of P135:Y6 to 15.11%, which is higher than P133:Y6 (10.24%). Therefore,18 these investigations confirm the pronounced potential of fused ring DTNID as an19 acceptor unit for emerging D–A copolymers for PSCs with high efficiency